1. Field of Invention
The present invention relates to a canister used in a vehicle, and more particularly, to a canister with dual air flow paths configured to divide an inner space of an air entrance of the canister into two spaces and allow air to flow in from an outdoor atmosphere through one space between two spaces in a purging operation and discharge fuel evaporation gas to the outdoor atmosphere through the other space when the fuel evaporation gas is discharged in order to prevent pressure in a fuel tank from being raised.
2. Description of Related Art
A fuel system apparatus of a vehicle as an apparatus that stores and supplies fuel consumed in an engine includes a fuel tank storing fuel, a fuel pump supplying the fuel in the fuel tank to a vaporizer, a fuel filter removing impurities of the fuel, and a canister collecting and storing evaporated gas of fuel vaporized in the fuel tank.
The canister absorbs the fuel evaporated gas with activated carbon embedded therein if the engine is stopped and desorbs the fuel evaporated gas absorbed in the activated carbon by using intake pressure of air injected from the outside of the canister when the engine is actuated, and then mixes the desorbed fuel evaporated gas with air and supplies the mixed gas to an intake system of the engine. In addition, the operation of supplying the fuel evaporated gas to the engine is generally as a purge operation.
FIG. 1 shows a configuration a general canister. The canister has a housing 1 configuring an appearance thereof and activated carbon 6 for absorbing and desorbing the fuel evaporated gas is charged in the housing 1.
In addition, an air entrance 2 that allows air to flow into the canister from an outdoor atmosphere when the canister performs the purge operation is formed in an upper part of the housing 1.
The air entrance 2 may discharge the fuel evaporated gas in the fuel tank to the outdoor atmosphere in order to prevent the internal pressure of the fuel tank from being raised.
An evaporated gas outlet 3 discharging the fuel evaporated gas absorbed in the activated carbon 6 to the intake system of the engine when the canister performs the purge operation is formed in the upper part of the housing 1.
An evaporated gas inlet 4 flowing in the fuel evaporated gas generated from the fuel tank when the engine is stopped is formed in the upper part of the housing 1.
Filters 5 are mounted on the air entrance 2, the evaporated gas outlet 3, and the evaporated gas inlet 4. The filters 5 serve to interrupt impurities such as dust contained in the air or fuel evaporated gas that is in and out.
However, while air from the outside is supplied to the air entrance 2 when the canister performs the purge operation, impurities such as dust are attached to the surface of the filter 5 installed in an opening at the side of the air entrance 2.
The sizes of pores of the filter 5 are routinely 10 μm. The reason therefor is that the sizes of the pores of the filter 5 are adjusted to be smaller than those of the minute powders of the activated carbon in order to prevent minute powders of the activated carbon from being discharged together while discharging the fuel evaporated gas in the fuel tank to an atmosphere.
Therefore, while impurities in the air having sizes similar to the sizes of the pores cannot pass through the filters 5 in the purge operation, most of the impurities are attached to the surface of the filter 5.
In this case, as shown in a detailed diagram of part A of FIG. 2, an impurity layer D is formed while the impurities attached to the filters 5 are fixed as a use time of the canister is lengthened.
In addition, since the impurity layer D formed on the surface of the filter 5 disturbs smooth flowing of air, outdoor air is not sufficiently supplied when the canister performs the purge operation, and as a result, the fuel tank may deformed or cracked while negative pressure is formed in the fuel tank.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.